The present technology relates to a finder optical system to observe an image display screen of a display device and an image capturing apparatus using the same.
In general, when a specification of a finder optical system used in an electronic view finder such as a digital camera and a video camera is designed, design flexibility is low. For example, if a size of the display device to display an image is specified, a focal length is determined inevitably once a view angle is specified. Also, an F value of the optical system is inevitably determined by the focal length determined and an angle of emergence of a light beam emitted from the display device.
As a lens configuration of the finder optical system in the related art, there is known a three lens configuration in a triplet type having positive, negative and positive refractive indicies from an image display screen side to an eyes side (for example, see Japanese Patent Application Laid-open Nos. 2010-266776, 2007-264179, 2004-258653 and 2002-082290).